Bioadhesive; preparation procedure and device for the application of a bioadhesive; and hardeners for a bioadhesive

ABSTRACT

The present invention relates to a bioadhesive that includes at least two constituents that are intended to be combined, for simultaneous, separate, or time-shifted use, i.e.: 1) a semi-liquid constituent (A) that includes, at a minimum, gelatin in an aqueous solution; and 2) A constituent (B), in gel or non-gel form, that includes, at a minimum, an aldehyde, with the exception of non-gel solutions consisting of formaldehyde, glutaraldehyde, or glyceraldehyde. The invention also relates to the use of succinic dialdehyde and of aldehyde solution sin gel form as hardeners in a bioadhesive, and further relates to a procedure for the preparation of the said bioadhesives and to a device for the application of the said bioadhesives.

The present invention relates to bioadhesives having a gelatin base andan aldehyde hardener; to a procedure for preparing the bioadhesives andto a device for their application; and also to hardeners for suchadhesives.

The use of adhesives having a base of gelatin and resorcinol, hardenedby an aldehyde (known generally as "GRA adhesives"), is known in thefield of human and animal surgery, and particularly in the field ofvascular surgery. More specifically, the use of GRF(gelatin-resorcinol-formol) adhesives has often been described inconnection with the gluing of tissues (cf. RBM, Vol. 4, No. 2(March/April 1982), page 147, and Nouvelle Presse Medicale, Vol. 4, No.10 (Mar. 8, 1975).

The gelatin was selected primarily because of its innocuousness andbecause of its hemostatic properties, and also because of its ability toreact with certain aldehydes, known as "hardeners". in order to form, byreticulation, an adhesive mass. The resorcinol also makes it possible tostrengthen the quality of this type of adhesion.

The use of certain aldehydes (such as 37 percent officinal formol, 25percent glutaraldehyde, or even a mixture of the latter two aldehydes in9:1 ratio) is known; however, these aldehydes are utilized only innon-gel solution. These aldehydes have the disadvantage of being toxicat such concentrations (with an LD₅₀ of 296 mg/kg for the formaldehydeand an LD₅₀ of 33.7 mg/kg for the glutaraldehyde).

The use of such GRF adhesives requires that the surgeon first spread thegelatin/resorcinol (GR) mixture over the dry surfaces of the organ to beglued; then spray, instill, or deposit by small drops, with the aid ofan intradermal syringe, the liquid hardener (i.e., the stabilizedaqueous formaldehyde solution) onto the GR mixture; and finally applythe adhesive-coated surfaces to one another (cf. the CNIMH files, Vol. 6(November-December 1984)). It is known that aqueous solutions offormaldehyde, glutaraldehyde, and glyceraldehyde, or mixtures thereof,can be utilized as liquid hardening agents.

This method requires a high degree of precision on the part of thesurgeon, particularly because of the necrotic effect of the formol. Infact, the aspersion of formol onto living tissue not involved in theadhesive procedure causes damage and necroses that are oftenirreversible. Up till now, the surgical technique has consisted of verycarefully protecting the adjacent tissue; however, these precautionsoften turn out to be insufficient. Furthermore, the risk of thesurgeon's pricking himself with a syringe full of formol is alwayspresent; and, even at very low doses, an injection of formol causes ashock to the practitioner, who may therefore be required to interruptthe operation.

The present applicants have now developed a bioadhesive that remediesthe major disadvantages of the known adhesives as described hereinabove.

Accordingly, the present invention relates to a bioadhesive thatincludes at least two constituents that are intended to be combined, forsimultaneous, separate, or time-shifted use, i.e.:

1) A semi-liquid constituent (A) that includes, at a minimum, gelatin inan aqueous solution; and

2) A constituent (B), in gel or non-gel form, that includes, at aminimum, an aldehyde, with the exception of non-gel solutions consistingof formaldehyde, glutaraldehyde, or glyceraldehyde.

In a preferred embodiment of the invention, the constituent (B) is ingel form, and the disadvantages described hereinabove are avoided, inaccordance with the invention, because hardeners in gel form are easierto handle than liquid hardeners, and prevent the risks of inadvertentaspersions and the consequent necroses, and do not require the use ofthe same syringes. The said adhesives are applied in connection with thegluing of human or animal tissues, and particularly in connection withthe gluing of arteries and aortas.

The first constituent (A) is customarily utilized in GRA adhesives. Itconsists of an aqueous solution of gelatin in semi-liquid form. It maycontain from 5 to 20 grams of gelatin for every 20 to 25 ml of distilledwater. The semi-liquid GR constituent usually contains approximately 15grams of gelatin for every 20 ml of distilled water.

The aqueous gelatin solution may also contain resorcinol orphloroglucinol, in the form of a mixture with the gelatin. Usually,approximately 4 to 6 grams of resorcinol or phloroglucinol are used forevery 20 to 25 ml of water, and the solution preferably containsapproximately 5 grams of resorcinol for approximately 15 grams ofgelatin and approximately 20 ml of water. Because the resorcinol is notnon-toxic, an adhesive that contains only a little resorcinol, or noneat all, may be useful.

In accordance with a preferred embodiment of the invention, theconstituent (B), which includes the hardening aldehyde, is in gel form,and preferably in the form of an aqueous gel. The gelling agents thatcan be utilized include all of the customary, currently available, andbiologically acceptable gelling agents that do not reach with thealdehydes. The gelling agents that can be utilized include, inparticular, agar-agar, karaya gum, silica powders, and the hydroxylatedand carboxylated derivatives of cellulose, such as hydroxyethylcellulose, carboxymethyl cellulose, and mixtures thereof.

In accordance with the invention, the aldehydes that can be utilized areselected from among officinal formaldehyde, glutaraldehyde,glyceraldehyde, succinic dialdehyde, sulfonyl-bis-acetaldehyde,1,8-octanedial 4-octene 1,8-dial, oxy-bis-acetaldehyde, and mixtures ofthese aldehydes.

In the second constituent (B) in gel form, the customary aldehydes areutilized at their customary concentrations for liquid hardeners, and mayoptionally be in the form of mixtures, as in liquid hardeners. Thepreferred aldehyde is succinic dialdehyde, whose utilization as ahardener for bioadhesives has not yet been described. This aldehyde iseffective at very low concentrations, on the order of 5 percent byweight of the hardener, thereby providing an advantage in view of thetoxicity of the aldehydes.

Among the mixtures, preference is given to mixtures of succinicdialdehyde and glutaraldehyde (in a ratio of 5:0.25).

The customary concentrations of aldehyde in liquid hardeners may reachvalues on the order of 1 to 50 percent by weight of aldehyde, and,typically, from 1 to 40 percent by weight for glutaraldehyde and from 1to 50 percent by weight for oxy-bis-acetaldehyde.

For succinic dialdehyde, the concentrations may range from 1 to 40percent, and preferably from approximately 5 to 20 percent.

Whereas the customary mixture consists of formol and glutaraldehyde (9parts by volume of 37-percent formol for 1 part of 40-percentglutaraldehyde), the succinic dialdehyde mixture contains, by weight inconstituent (B), from 40 to 50 percent succinic dialdehyde and from 0.2to 1 percent glutaraldehyde.

The gelling agent is optionally utilized, in an aqueous solution, inproportions on the order of 1 to 5 percent by weight, and preferably 2percent by weight. This proportion depends, on the one hand, on thegelling agent utilized, and, on the other hand, on the viscosity of thesemi-liquid constituent (A). In fact, during application, it may beuseful for the constituents (A) and (B) to have similar viscosities.

The invention also relates to aqueous solutions, in gel form, of thesaid aldehydes or mixtures thereof, which solutions may optionally bestabilized, and which are useful particularly as hardeners forbioadhesives.

The aldehyde gels obtained with the said products are stable at roomtemperature for at least one year. Furthermore, the initial aldehydecontent is maintained throughout the said period.

The invention also relates to the use of succinic dialdehyde as ahardener for bioadhesives. The bioadhesives that can be hardened by sucha succinic dialdehyde, in an aqueous solution or in an aqueous solutionin gel form, include, on the one hand, a semi-liquid constituent thatincludes, at a minimum, gelatin, and optionally resorcinol orphloroglucinol, and, on the other hand, an aldehyde constituent, inliquid or gel form, that includes at a minimum, as a hardener, succinicdialdehyde. The dialdehyde may optionally be mixed with anotherhardening aldehyde. In view of its high degree of effectiveness, thisdialdehyde is particularly well suited to use in gluing the liver, lung,spleen, pericardium, and kidney. Its effectiveness makes it possible toreduce the percentage of aldehyde utilized, to approximately 5 percentby weight in constituent (B).

In the said bioadhesives that contain succinic dialdehyde, the succinicdialdehyde (whether or not it is utilized in constituent (B)) isutilized at concentrations ranging from approximately 1 to 40 percent,and preferably from 5 to 20 percent, by weight.

The present invention also relates to a procedure for the preparation ofa bioadhesive, characterized by the fact that, on the one hand, asemi-liquid constituent (A) that includes, at a minimum, gelatin in anaqueous solution, and, on the other hand, a constituent (B) thatincludes, at a minimum, one aldehyde, with the exception of non-gelsolutions consisting of formaldehyde, glutaraldehyde, or glyceraldehyde,are mixed and applied in the form of superimposed layers.

The two constituents are preferably mixed immediately prior to use.

To prepare the adhesive, the semi-liquid constituent (A) is prepared, onthe one hand, by diluting the gelatin (and, optionally, the resorcinol)in distilled water and, on the other hand, by introducing the aldehyde(and, optionally, the gelling agent) into the water.

When the adhesive is ready for use, constituent (A) is customarilypre-heated, in a water-bath, to a temperature on the order of 28 to 40degrees [Celsius], and preferably to a temperature on the order of 37degrees [Celsius].

In accordance with the invention, the aldehyde gels are utilized at roomtemperature, but may also be utilized at temperatures on the order ofhuman temperature, i.e., temperatures on the order of 28 to 40 degrees[Celsius].

The use of hardeners in gel form makes it possible to utilized a deviceconsisting of a syringe of the type with two bodies, or any other meansthat are appropriate for mixing and quantifying, in appropriateproportions, constituent (A) and constituent (B) containing the selectedaldehyde at the concentration that is most appropriate for the type ofgluing in question.

This operational procedure frees the surgeon from the need to create themixture himself extemporaneously, or to apply the adhesive in two steps.The result is not only a saving in terms of time, but also a betterquantification of the constituents, and, finally, avoidance of the riskof erroneously applying the hardener to the tissues adjacent to thetissues to be glued.

Furthermore, for the application of constituent (B) in non-gel form, itis possible first to apply constituent (A) in the form of a layer on atleast one of the surfaces of the tissues to be glued, and then to injectconstituent (B) into the said layer before applying the tissues to oneanother.

Thus, the invention relates to a device having two compartments, one ofwhich contains constituent (A) and the other of which containsconstituent (B), as defined hereinabove.

A suitable device consists of a syringe of the type with two bodies, oneof whose bodies contains a constituent (A), which includes, at aminimum, gelatin in an aqueous solution, and whose other body contains aconstituent (B), in gel form or in non-gel form, in accordance with thepresent invention, which includes at least one aldehyde.

In a particular embodiment of the invention, a syringe with two bodiesis utilized that allows the simultaneous application of the twocomponents, or the immediate mixture of the two components at the outletof the syringe.

Dual-body syringes of this type are known under the trade name"Duploject".

Preferably, and particularly in this mode of application, constituents(A) and (B) are utilized whose viscosities are similar.

The bioadhesives prepared in accordance with the invention have beenshown to be particularly effective, especially in connection with aorticgluing and in connection with the gluing of the pericardium, lung,liver, spleen, and kidney. Generally speaking, the adhesives inaccordance with the invention can be utilized in bone, vascular,visceral, and dental surgery.

The following examples provide illustrations of the invention, withouthowever limiting its scope.

EXAMPLE 1

Constituent (A)

A GR paste is obtained through the dissolution, in 20 to 25 ml ofdistilled water, kept at a temperature of 50 degrees C. in a water-bath,of 2 grams of a mixture of resorcinol and powdered gelatin, inproportions of 1/4 and 3/4, respectively. The proper consistency of themixture is obtained within 30 minutes, through the use of a planetarystirring device that is operated slowly in order to prevent theformation of air-bubbles.

Constituent (B)

One volume consisting of an aqueous solution of glutaraldehyde (25percent by weight) is added to 9 volumes of an aqueous solution offormol (37 percent by weight), followed by 1.5 to 2 by weight ofhydroxyethyl cellulose. The resulting mixture is heated, undermechanical stirring, in a water-bath until the hydroxyethyl cellulose iscompletely dissolved. After cooling to room temperature, a gel isobtained whose viscosity is similar to that of the GR mixture. Theresulting viscosity is a function of the quantity of hydroxyethylcellulose utilized. The percentage indicated in the present example isnot limitative.

The mixture of constituents (A) and (B) is applied to the tissues to beglued, and the said tissues are applied to one another.

EXAMPLE 2

Constituent (A)

A pre-constituted GR paste is utilized, as obtained from thegelatin-resorcinol-water mixture described in Example 1 above. The saidpaste is placed in a sterile tube ready for use, after heating for 5 to10 minutes, in a sterile water-bath at a temperature of 45 degrees C.

Constituent (B)

A quantity of carboxymethyl cellulose (2 percent by weight) is added toan aqueous solution containing succinic dialdehyde (5 percent by weight)and glutaraldehyde (0.25 percent by weight). The resulting mixture isheated and stirred in the same way as in Example 1 above until a gel (B)is obtained.

The mixture consisting of constituents (A) and (B) is applied to thetissues to be glued, and the said tissues are applied to one another.

EXAMPLE 3

The same procedure described in Example 2 above is followed, but withthe use of a 5-percent aqueous solution of succinic dialdehyde, and withno glutaraldehyde, as constituent (B).

The mixture consisting of constituents (A) and (B) is applied to thetissues to be glued, and the said tissues are applied to one another.

EXAMPLE 4

Constituent (A) is the same as in Example 1 above.

An aqueous gel is prepared that contains 36 percent by weight offormaldehyde, 4.5 percent by weight of succinic dialdehyde, and 2percent by weight of carboxymethyl cellulose. The resulting mixture isheated and stirred in the same way as in Example 1 above until a gel (B)is obtained.

The mixture consisting of constituents (A) and (B) is applied to thetissues to be glued, and the said tissues are applied to one another.

EXAMPLE 5

Constituent (A)

This constituent is identical to the one in Example 1 above.

Constituent (B)

An aqueous solution containing succinic dialdehyde (20 percent byweight) is utilized.

A layer of constituent (A) is applied to the tissues to be glued. Thensolution (B) is injected into the layer of constituent (A). The tissuesto be glued are then applied to one another.

I claim:
 1. A bioadhesive composition comprising:a first constituentincluding an aqueous solution of gelatin; and a second constituentmaintained separately from the first constituent and including succinicdialdehyde present in an amount sufficient to promote cross-linking ofthe gelatin in the first constituent; wherein the first and secondconstituents may be combined and applied to tissue as an adhesive.
 2. Abioadhesive composition as in claim 1, wherein the second constituent isa gel.
 3. A bioadhesive composition as in claim 2, wherein the secondconstituent comprises a gelling agent selected from the group consistingof agar, karaya gum, silica powder, hydroxyethyl cellulose,carboxymethyl cellulose, hydroxylated cellulose, and carboxylatedcellulose.
 4. A bioadhesive composition as in any one of claims 1-3,wherein the aqueous solution of gelatin includes from 5 g to 20 g ofgelatin for every 20 ml to 25 ml of water.
 5. A bioadhesive compositionas in any one of claims 1-3, wherein the second constituent comprisesfrom 1% by weight to 40% by weight succinic dialdehyde.